Effect of ultrasound doses on the amyloid-beta 25-35 induced PC12 apoptosis.

Previous studies have shown that Amyloid-beta (A beta) may induce the apoptosis of neuronal cells leading to the syndrome of Alzheimer's disease (AD). The stimulation by optical energy was found able to greatly inhibit A beta induced apoptosis. This study aims to further explore the effect of different doses of ultrasonic insonification on neuronal cells. Experiments were carried out using PC12 cells added with A beta 25-35 of a 20 microM during pre-cultured preparation. These cells were respectively stimulated by a single and multiple insonification for three minutes with a 20% duty cycle ultrasound of the intensity of 150 mW/cm2 (SATA). The cellular response was assessed, using the microscopic morphology, cell death measured by the typical MTT assay, and annexin V/PI double stain assay, for 8 times within 72 hours after that cells were stimulated. Results showed that both stimulations by single and multiple does ultrasound may diminish A beta induced neuronal cells apoptosis. The diminish effects tend to be time dependent corresponding to 72 and 12 hours after ultrasound exposure by single and multiple insonification, respectively. Fluorescence stain results indicated that those cells stimulated by a single dose ultrasound tended to slightly inhibit A beta-induced PC12 to apoptosis. This study demonstrated that the effect of diminishing neuronal cells from apoptosis could be regulated with the insonation of appropriate ultrasonic doses.